+/*
+ * Redirty an inode: set its when-it-was dirtied timestamp and move it to the
+ * furthest end of its superblock's dirty-inode list.
+ *
+ * Before stamping the inode's ->dirtied_when, we check to see whether it is
+ * already the most-recently-dirtied inode on the s_dirty list. If that is
+ * the case then the inode must have been redirtied while it was being written
+ * out and we don't reset its dirtied_when.
+ */
+static void redirty_tail(struct inode *inode)
+{
+ struct super_block *sb = inode->i_sb;
+
+ if (!list_empty(&sb->s_dirty)) {
+ struct inode *tail_inode;
+
+ tail_inode = list_entry(sb->s_dirty.next, struct inode, i_list);
+ if (!time_after_eq(inode->dirtied_when,
+ tail_inode->dirtied_when))
+ inode->dirtied_when = jiffies;
+ }
+ list_move(&inode->i_list, &sb->s_dirty);
+}
+
+/*
+ * requeue inode for re-scanning after sb->s_io list is exhausted.
+ */
+static void requeue_io(struct inode *inode)
+{
+ list_move(&inode->i_list, &inode->i_sb->s_more_io);
+}
+
+static void inode_sync_complete(struct inode *inode)
+{
+ /*
+ * Prevent speculative execution through spin_unlock(&inode_lock);
+ */
+ smp_mb();
+ wake_up_bit(&inode->i_state, __I_SYNC);
+}
+
+/*
+ * Move expired dirty inodes from @delaying_queue to @dispatch_queue.
+ */
+static void move_expired_inodes(struct list_head *delaying_queue,
+ struct list_head *dispatch_queue,
+ unsigned long *older_than_this)
+{
+ while (!list_empty(delaying_queue)) {
+ struct inode *inode = list_entry(delaying_queue->prev,
+ struct inode, i_list);
+ if (older_than_this &&
+ time_after(inode->dirtied_when, *older_than_this))
+ break;
+ list_move(&inode->i_list, dispatch_queue);
+ }
+}
+
+/*
+ * Queue all expired dirty inodes for io, eldest first.
+ */
+static void queue_io(struct super_block *sb,
+ unsigned long *older_than_this)
+{
+ list_splice_init(&sb->s_more_io, sb->s_io.prev);
+ move_expired_inodes(&sb->s_dirty, &sb->s_io, older_than_this);
+}
+
+int sb_has_dirty_inodes(struct super_block *sb)
+{
+ return !list_empty(&sb->s_dirty) ||
+ !list_empty(&sb->s_io) ||
+ !list_empty(&sb->s_more_io);
+}
+EXPORT_SYMBOL(sb_has_dirty_inodes);
+